1. Field of the Invention
The present invention relates to the field of photography and, more specifically, to particular structural details that are incorporated into a virtually automatic photographic apparatus intended for use with self-processable type film units; the invention being directed to features of a housing that serves to support a film transport and processing system and retain a film unit after it has been processed.
2. Description of the Prior Art
Virtually automatic cameras that utilize so-called integral negative-positive diffusion transfer film products generally include film advancing and processing mechanisms that perform a series of operations during a picture taking cycle which transport an exposed film unit from an interior exposure station to exterior portions of the camera where it is then releasably retained by the camera so that a user may remove it. In this regard, refer to, for example, U.S. Pats. Nos. 3,709,122; 3,766,118 and 3,810,211 for a detailed description of mechanisms for performing the aforementioned operations of fim advancing, processing and port-processing retention, respectively. These patents collectively disclose a film advancing arrangement having a pick member that is adapted to enter a slot in the rear end of a cassette of film units, one stacked on the other, to engage the trailing edge of a foremost film unit, after its exposure, and advance it out of an elongated exit slot located in a forward wall of the cassette into a pressure generating gap formed between a pair of juxtaposed rotating fluid processing rollers. After the film unit is brought into engagement with the rollers, it is then further advanced by them while they simultaneously progressively spread a processing fluid across the film unit as it moves through them from its leading to its trailing edge. Once the leading edge of the film unit passes through the pressure gap, it is intercepted by a deflecting plate that bends it toward an exit slot that is spaced away from the gap and offset with respect to the path the film unit would naturally follow if the deflecting plate were not present. The deflecting plate influences fluid processing and also provides a light shading function and, as well, cooperates with portions of the exit slot to provide the film retention function previously mentioned.
Each time a user initiates a cycle, the sequence of events just described is repeated in consecutive fashion until, one after another, the supply of film is exhausted. It is therefore possible, if ech film unit in its turn is not removed, to accumulate a number of them in the film retention arrangement.
In presently available commercial cameras as, for example, Polaroid Corporation's SX-70 Land Camera which incorporates the features of the aforementioned patents, the accumulation of a number of film units in the film retention arrangement is not a problem for a variety of reasons.
First, the retention arrangement has the capability of holding a number of film units without affecting other camera functions such as processing or light shading. This is possible because the deflecting plate that provides the light shading function is nonmoving once the camera is placed in its picture taking mode. Also the bend induced in the film unit by the deflecting plate to influence the processing fluid distributing is relatively gentle so that small changes in the degree of film bending caused by the accumulated film units do not change processing conditions appreciably.
Secondly, after a certain number of film units have accumulated, subsequently advanced film units automatically begin to push those retained out of the camera so that jamming is precluded.
However, the present invention is concerned with a camera having a deflecting plate that induces a different bend in the film unit and further includes a light shade that is actuated by the advancing film unit itself, i.e., is moveable. These two features make it necessary to either manually remove each film unit after it is advanced to the exterior of the camera or provide some means within the camera that will automatically assure that all film units are subject to the same conditions during a picture taking cycle. These requirements become critical because the geometry producing the bend makes it inherently more sensitive to any dimensional changes in the path of travel that a film unit follows during processing. Any accumulation of film units in the film retention arrangement would produce significant dimensional changes which would have an undesirable influence on processing fluid distribution. Moreover, it is possible for subsequently advancing film units to bypass the moveable light shade and thereby circumvent its purpose.
For the above reasons there is a need to have a structural solution to the problem of being able to automatically eject a processed film unit from the film retention mechanism in order to clear the way for a subsequently processed film unit upon emerging from the processing apparatus. This may be accomplished by having the emerging film unit push the prior processed film unit out of the camera. In general terms, this solution has been disclosed in some prior art patents such as U.S. Pat. Nos. 3,541,937 and 3,541,938. However, in these disclosures the cameras have not been of the virtually automatic type and the film units do not have the same characteristics that are associated with the type of film that is being used in the present invention. In addition, the path of travel of the film unit in these patents is straight rather than bent. In short, the problems addressed are not the same as those encountered in the present invention.